Chunju Xu

Formation of flower-like magnesium hydroxide microstructure via a solvothermal process

Flower-like magnesium hydroxide (Mg(OH)2) microstructure composed of many sheet-like nanopetals was prepared on a large scale via a solvothermal reaction at 200°C for 24 h. Water and ethanol mixed solution was employed as solvent and no additional surfactant was involved during the synthetic process. The Mg(OH)2 microflowers were characterized by XRD, SEM, HRTEM, and UV-vis techniques. The average size of single flower is about 2 µm and the thickness of the petals ranges from 20 to 30 nm. The temperature and volume ratio of water to ethanol were found to be key roles for controlling the morphology of Mg(OH)2 products. The assembled petals of the Mg(OH)2 microflowers became thicker and smoother with the amount of water decreased in the mixed solvent. The present method is low cost, simple handle and environmentally benign, thus, it can be relatively easy to be scaled up for industrial production.

Facile fabrication of porous flower-like α-Fe2O3 microspheres and their applications for water treatment

Abstract Flower-like α-Fe2O3 microspheres with an average diameter of about 1.5 μm were successfully synthesised with the assistance of ethylenediamine (EDA) through a facile high temperature solution method in ethylene glycol (EG) solvent. The morphologies and microstructure of the samples were characterised by scanning electron microscopy (SEM) and X-ray diffraction techniques. It was found that the size and morphology of the products were greatly influenced by the amount of EDA, EG and refluxing time, and a possible growth mechanism of such flower-like shape was proposed based on the controlled experiments. Because of the high specific surface area and porous structure, the α-Fe2O3 microflowers showed excellent adsorption performances with maximum removal capacities of 212 mg g−1 for Congo red in waste water treatment. The samples obtained from controlled experiments were also tested for the adsorption capacities, and the comparative dates were displayed distinctly. The prepared porous α-Fe2O3 spheres might have promising application in water treatment including the adsorption for toxic metal ions and the photocatalytic degradation.

A general route to the synthesis of PS/metal composites and their conversion to metal hollow microspheres

In this work, we put forward a simple and universal electroless plating approach to synthesize polystyrene/metal (PS/M) composite spheres, and hollow metal (e.g. Ni, Co, Cu) structures were also obtained after removing the PS core. Monodisperse PS microspheres were initially synthesized via a dispersion polymerization, and then these PS spheres activated with Pd served as templates for the synthesis of PS/M core–shell composite. The parameter of temperature was investigated in details, which strongly influenced the quality and morphology of metal coatings. Based on the above core–shell structures, the PS core template could be removed by ethyl acetate, and metal hollow spheres were formed finally. X-ray diffraction and scanning electron microscopy characterizations indicated that elemental Ni, Co, and Cu coatings with highly pure phase were successfully deposited onto the surfaces of PS microspheres. Such PS/M composites with low density would have wide applications in electromagnetic shielding fields.

Facile and controlled synthesis of FeCo nanoparticles via a hydrothermal method

Magnetic FeCo alloy nanoparticles have been synthesized by reduction of FeSO4 and CoCl2 with hydrazine in concentrated alkaline media via a hydrothermal route. The size could be controlled by synthetic conditions such as reaction time and temperature, respectively. The obtained samples were characterized by XRD, SEM, TEM, and VSM techniques. Magnetic investigations show the ferromagnetic behavior with saturation magnetization higher than 148.2 emu/g and maximum coercivity up to 411.0 Oe at room temperature. The present method is simple, inexpensive, surfactant-free, and may stimulate technological interests. Such FeCo alloy nanoparticles may have potential applications in biomedical field and magnetic storage devices.

Growth of wheel-like ZnO microstructures at low temperature

Abstract Wheel-like ZnO microstructures were synthesised via a simple and environmental benign chemical bath deposition at 90°C. The crystalline structure and shapes of the prepared ZnO were characterised by XRD and SEM techniques respectively. Such novel ZnO microstructures were constructed with many microsheets radiated from a hollow core, and the average size was ∼20 μm. Temperature and concentration of polyvinylpyrrolidone (PVP) were found to play important role in the formation of wheel-like morphology, and ZnO bidisks with different aspect ratio were also obtained by precisely synthesis control. The photoluminescence spectrum of the sample possessed a relatively strong UV emission at 382 nm and a very broad visible light emission.